Electrical stimulation of the right and left phrenic nerve has been used for treating respiratory insufficiency, e.g. in paralysis, apnea, or other respiratory conditions as recognized by Creasy et al. Electrical Stimulation To Restore Respiration, Journal of Rehabilitation Research and Development, Vol. 33 No. 2, April 1996, pp 123-132. For example, U.S. Pat. No. 7,979,128 to Tehrani et al. (hereinafter Tehrani et al.) asserts that phrenic nerve stimulation can gradually control breathing in order to treat obstructive sleep apnea. Tehrani et al., discloses in claim 1 that electrical stimulation is delivered when an obstructive respiratory event is detected. Electrical stimulation is applied during a first selected intrinsic inspiration cycle at a first delay from an onset of the first intrinsic inspiration cycle. Electrical stimulation is then applied during a second intrinsic inspiration cycle at a second delay from an onset of the second intrinsic cycle. Electrical stimulation is again applied during one or more subsequent intrinsic breaths such that each stimulation is applied with a delay from an onset of each subsequent intrinsic breath such that the delay in each subsequent breath reduces from a previous delay until the stimulation is synchronous with a start of each subsequent intrinsic inspiration wherein the electrical stimulation is provided to tissue associated with the diaphragm of the patient at least in part during the intrinsic inspiration cycle in accordance with the electrical stimulation protocol until the sensed respiration has reached a normalized respiration such that ventilatory stability is improved. Variable delay to deliver stimulation to the phrenic nerve is used to achieve a synchronous normalized breathing pattern and does not provide a more robust breathing pattern
U.S. Pat. No. 5,265,604 to Vince discloses innervating one of both denervated diaphragms of a patient synchronously. Muscle contraction is detected through a sensor near the pharyngeal muscle within the pharynx at the onset of inspiration and the intensity of the muscle contraction, and produces a signal representative of rate and intensity of pharyngeal muscle contraction at onset of inspiration.
U.S. Pat. No. 7,363,085 to Benser et al. discloses that phrenic nerve stimulation is used to avoid Cheyne Stokes Syndrome (CSS) that typically occurs during sleep. CSS involves tidal volume of the lungs oscillating between hyperpnea and hypopnea or apnea with a periodicity 70 seconds. Benser et al. senses respiratory data from the patient. When the respiratory data indicates that the upper airway may collapse, electrical stimulation is delivered to the phrenic nerve in order to prevent the upper airway from collapsing.
A need remains for an implantable medical device to automatically deliver electrical stimulation to the right or left phrenic nerve through stimulation methods and associated apparatus for effectively delivering phrenic nerve stimulation for respiration therapies.